Wackadoodle

Part of speech: noun

Definitions

1. Behaving in an extremely silly, irrational, or eccentric manner; completely absurd or crazy
2. Exhibiting mentally unstable or wildly unusual conduct
3. Showing signs of strange, impractical or irrational traits

Etymology: "Wacko" and "wacky" are the likely bases for "wackadoodle," with the playful ending "-doodle" tacked on for extra silliness. English has many such reduplicated or nonsense-sounding endings, such as "hoodle" and "noodle," and "doodle" fits that pattern. Its exact coinage is uncertain, and it appears to be informal American slang. It describes a person whose behaviour is so eccentric that it seems unhinged, and it is mostly used humorously rather than as a clinical term.

Synonyms: crazy, eccentric, quirky

Antonyms: sensible, reasonable